Negative control ofBAK1 by protein phosphatase 2A during plant innate immunity

• DOI: 10.15252/embj.201488698
• Publication Date: 2014-08-02T05:47:43Z
• Authors: Cécile Segonzac; Alberto P Macho; Maite Sanmartín; Vardis Ntoukakis; José Juan Sánchez...; Cyril Zipfel
• Keywords: Pathogen-associated molecular pattern; Plant Immunity

AbstractRecognition of pathogen‐associated molecular patterns (PAMPs) by surface‐localized pattern‐recognition receptors (PRRs) activates plant innate immunity, mainly through activation of numerous protein kinases. Appropriate induction of immune responses must be tightly regulated, as many of the kinases involved have an intrinsic high activity and are also regulated by other external and endogenous stimuli. Previous evidences suggest thatPAMP‐triggered immunity (PTI) is under constant negative regulation by protein phosphatases but the underlying molecular mechanisms remain unknown. Here, we show that protein Ser/Thr phosphatase type 2A (PP2A) controls the activation ofPRRcomplexes by modulating the phosphostatus of the co‐receptor and positive regulatorBAK1. A potentialPP2A holoenzyme composed of the subunits A1, C4, and B’η/ζ inhibits immune responses triggered by severalPAMPs and anti‐bacterial immunity.PP2A constitutively associates withBAK1in planta. Impairment in thisPP2A‐based regulation leads to increased steady‐stateBAK1 phosphorylation, which can poise enhanced immune responses. This work identifiesPP2A as an important negative regulator of plant innate immunity that controlsBAK1 activation in surface‐localized immune receptor complexes.